# mccc-message-cpp

**Repository Path**: liudegui/mccc-message-cpp

## Basic Information

- **Project Name**: mccc-message-cpp
- **Description**: 基于 MCCC 无锁消息总线的 SendMessage/PostMessage 线程间消息传递模式
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2026-02-16
- **Last Updated**: 2026-02-21

## Categories & Tags

**Categories**: Uncategorized

**Tags**: Cpp, 消息传递, MCCC, 多线程, SendMessage

## README

# mccc-message-cpp

SendMessage/PostMessage inter-thread messaging pattern built on [MCCC](https://gitee.com/liudegui/mccc-bus) lock-free message bus.

## Overview

This project demonstrates how to replace traditional `mutex + priority_queue + promise/future` inter-thread messaging with MCCC's lock-free MPSC ring buffer. It provides a thin `MessageService` wrapper that maps Windows-style `SendMessage` (synchronous) and `PostMessage` (asynchronous) to MCCC primitives.

## Key Features

| Feature | Traditional (mutex) | MCCC-based |
|---------|-------------------|------------|
| Thread safety | `std::mutex` + `std::condition_variable` | Lock-free CAS (MPSC) |
| Memory allocation | `std::shared_ptr<std::promise<int>>` per sync msg | Pre-allocated `ResponseSlot` pool |
| Priority | `std::priority_queue` (O(log n) insert) | Admission control (O(1), 3 levels) |
| Type safety | `int msg_id` + `int w_param` | `std::variant<AsyncMessage, SyncRequest>` |
| Backpressure | None (unbounded queue growth) | Priority-based admission thresholds |

## Architecture

```
Producer Threads              Consumer Thread
 (SendMessage/PostMessage)     (ProcessBatch)
    |                              |
    | lock-free CAS enqueue        | batch dequeue
    v                              v
+------------------------------------------+
|     MCCC AsyncBus (MPSC Ring Buffer)     |
|  Priority Admission: HIGH > MEDIUM > LOW |
+------------------------------------------+
                                   |
                         +---------+---------+
                         |                   |
                   AsyncMessage         SyncRequest
                   (fire & forget)      (response slot)
                         |                   |
                    handler(...)         handler(...) -> result
                                             |
                                      ResponseSlot.SetResult()
                                             |
                                      Producer.WaitResult()
```

## Build

```bash
mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Debug
make -j$(nproc)
ctest --output-on-failure
```

### CMake Options

| Option | Default | Description |
|--------|---------|-------------|
| `MCCC_MESSAGE_BUILD_EXAMPLES` | ON | Build example programs |
| `MCCC_MESSAGE_BUILD_TESTS` | ON | Build Catch2 tests |

## Examples

- **basic_demo** -- Mirrors the original CSDN article's `main()` function
- **priority_demo** -- MCCC priority admission control (HIGH/MEDIUM/LOW)
- **sync_async_demo** -- Multi-producer concurrent SendMessage/PostMessage

## Tests

8 test cases covering:
- `ResponsePool` lock-free acquire/release
- `PostMessage` async delivery
- `SendMessage` sync request-reply
- Multi-producer concurrent mixed sync/async
- Service lifecycle management

All tests pass under ASan + UBSan.

## Dependencies

- C++17 compiler (GCC 7+ / Clang 5+)
- [MCCC](https://gitee.com/liudegui/mccc-bus) (auto-fetched via CMake FetchContent)
- [Catch2 v3](https://github.com/catchorg/Catch2) (auto-fetched for tests)

## License

MIT